[Gate-users] How to find the relation between different hits? (Astrid Velroyen)

Marcin Balcerzyk m.balcerzyk at pluri.ucm.es
Mon Nov 9 12:58:38 CET 2009

Dear Astrid


For detailed look at particular hits and coincidences I think there is no
option other than store hits (singles and coincidences) in ASCII file with
some reasonable simulation time and file size limit:

/gate/output/ascii/setOutFileSinglesFlag 1

/gate/output/ascii/setOutFileSinglesFlag 1

/gate/output/ascii/setOutFileCoincidencesFlag 1

/gate/output/ascii/setOutFileSizeLimit 10000000


You can identify events by IDEvent in Hits, Singles and Coincidences file
and roughly by the time of the event. There you can do some work, being
closer to the raw data and not only to histograms. The columns are described
in section 10.1.4 of the user's guide. In my case of PET camera of most
general type the columns are the following for Hits file (my naming in
accordance with root leaves more less): IDRun  IDEvent
IDprimPart          IDSource              VolID1   VolID2   VolID3
VolID4   VolID5   VolID6   TimeStamp         EnergyDep          RangePart
EventX  EventY  EventZ  PartHitCode                IDMotherPart    Idphoton
NumCompt        ProcNum             ComptNum        ProcName


The most interesting for you would be ProcName which describes what happened
with gamma. Shortened words in that column are descriptive (msc eIoni compt
LowEnRayleigh compt phot eIoni as examples ). Then you may find some info on
the shower with IDMother and Idphoton which are unique for each event I
think, and then start to repeat. Note, that your Physics part of mac file
determines how closely the hits are followed. The attached XLS file shows
example output from 3 events for hits and from 4 coinc. They are not from
the same simulation. I work at times with binary Excel 2007 files of hits
with 1M hits using filtering. You may try some database software if you do
not have Excel. 


Kind regards


Marcin Balcerzyk

Universidad Compultense de Madrid


Message: 1

Date: Thu, 05 Nov 2009 11:14:46 +0100

From: Astrid Velroyen <astrid at velroyen.de>

Subject: [Gate-users] How to find the relation between different hits?

To: Gate-users at lists.healthgrid.org

Message-ID: <4AF2A596.2040708 at velroyen.de>

Content-Type: text/plain; charset=ISO-8859-15; format=flowed


Dear GATE users,


I have got a question about how to analyze a GATE Hits simulation with
.root-Output. I'd like to be able to identify which hits belong to the same
incident gamma quantum. That means, that I want to keep track of of each
photon and find out which way it has gone, if it has left energy in
different crystals and so on.

I'm not sure which of the histogrammed data in the root output can provide
this information, the User's Guide does not give any detailed information
and I already looked up the GateCrystalHit.hh, where the comments do not
more than repeat the variable names.

Can anyone clarify what means trackID, parentID, photonID, primaryID,
eventID, and runID? Can anything of these data be used to follow the ways of
one gamma quantum coming out of my gamma beam source?

I tried to get the meaning of each of these histograms by looking how many
bins I have for a Hits list with about 1,000,000 entries:

TrackID is something between 1-7, parentID between 1-5.

PhotonID is always 1; I guess it just distinguishes between the two
annihilation photons, which I don't have, because I defined a simple gamma
beam source.

PrimaryID is also always 1.

EventID has 300*10^3 bins, maybe this is what I am looking for?

runID is always 1.


Has anyone of you experience with analyzing a hits output and can give me
some advice? Thanks.










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